The Dept. of Homeland Security has awarded eight contracts to companies to develop prototypes for the Trump administration’s proposed wall along sections of the nearly 2,000-mile U.S.-Mexico border. The contracts are divided evenly between concrete and nonconcrete options. DHS’s Customs and Border Protection agency didn’t specify what sort of materials would be used in the nonconcrete barriers.

Both types of walls would be 18 ft to 30 ft high. DHS announced the concrete-prototype awards on Aug. 31 and the “other than concrete” wall awards on Sept. 7. The cost of each prototype contract is in the $300,000-to-$500,000 range, said Carlos A. Diaz, a Customs and Border Protection spokesman, in an email.

Caddell Construction Co. LLC, Montgomery, Ala., and W. G. Yates & Sons Construction Co., Philadelphia, Miss., each was awarded one concrete and one nonconcrete wall contract. The agency also awarded concrete-prototype contracts to Fisher Sand & Gravel Co., Tempe, Ariz., and Texas Sterling Construction Co., Houston.

The other nonconcrete selectees are KWR Construction Inc., Sierra Vista, Ariz., and ELTA North America Inc., Annapolis Junction, Md. Customs and Border Protection said both sorts of prototypes will enable it “to evaluate the potential for new wall and barrier designs” that could complement its recently used designs.